Cylinder Works Big Bore Kit. Unlock your bike's hidden potential with the power producing and durable Cylinder Works big bore kit. O.E.M. appearing +1 mm to +4 mm big bore cylinder kit, a hand-matched, forged Vertex big bore piston and top-end gasket kit. These kits offer you an affordable way to increase horsepower and engine displacement without giving your secret away to your competition. Cylinder - New, not remanufactured, cast aluminum nickel silicon carbide (NSC) electroplated big bore cylinder that appears just like an O.E. cylinder. NSC is a composite of a nickel and silicon carbide, providing an excellent wear resistant surface with oil retention capabilities. Cylinders are then diamond honed to the exact bore dimension and proper surface finish to ensure the proper ring seal and oil retention.